Interesting and useful, but not in V1.
/ ht@inf.ed.ac.uk (Henry S. Thompson) was heard to say:
| I gave a presentation on the Last Call WD to some of the XML people at
| MSFT on Friday, and got a pleasantly positive reception.
|
| One specific question they were interested in, looking towards very
| large scale data processing with parallel hardware available, was
| whether we supported Google 'map-reduce' style decomposition. I
| mentioned the inherent parallelisability of the overall architecture,
| but realised we did not have anything which would directly support
| such decomposition. Maybe we should consider it. . .
|
| We already have 'map' -- it's just for-each with a select pattern on
| its input.
|
| Here's an example of how it could be used along with a new 'reduce'
| construct:
|
| Stipulate we have a pipeline which can construct an index for a book
| chapter. Here's how we index the whole book:
|
| <for-each select='//chapter'>
| [compute index]
| </for-each>
|
| <reduce name='r'>
| <input port="seed">
| <inline>
| </bookIndex>
| </inline>
| </input>
|
| <merge-two-indices>
| <input port='book'>
| <pipe port='seed' step='r'/>
| </input>
| </merge-two-indices>
|
| </reduce>
|
| where merge-two-indices has two inputs, primary a chapter index and
| secondary a book index, and one output, a new book index merging in
| the chapter index.
|
| reduce takes a primary sequence input and a secondary single input
| (the seed) and a subpipeline. It runs the subpipeline repeatedly,
| supplying each member of the sequence in turn as the default input and
| first time the seed, and subsequent times the output of the previous
| round, as the 'seed' input. Output is the output of the subpipeline
| From the last iteration.
|
| Such a construct would give us a way of addressing our current lack of
| open-ended/runtime input/output cardinality.
|
| ht
| --
| Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
| Half-time member of W3C Team
| 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
| Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
| URL: http://www.ltg.ed.ac.uk/~ht/
| [mail really from me _always_ has this .sig -- mail without it is forged spam]
Be seeing you,
norm
--
Norman Walsh <ndw@nwalsh.com> | Do not condemn the judgement of another
http://nwalsh.com/ | because it differs from your own. You
| may both be wrong.-- Dandemis